Effects of salinity stratification on turbulence in the South Passage of the Changjiang River Estuary

Wang Jiacheng; Jiang Chenjuan; Li Weihua; Wang Yajun

doi:10.12284/hyxb20250133

Volume 47 Issue 12

Dec. 2025

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Wang Jiacheng，Jiang Chenjuan，Li Weihua, et al. Effects of salinity stratification on turbulence in the South Passage of the Changjiang River Estuary[J]. Haiyang Xuebao，2025, 47(12)：25–34 doi: 10.12284/hyxb20250133

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Effects of salinity stratification on turbulence in the South Passage of the Changjiang River Estuary

doi: 10.12284/hyxb20250133

1.
College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou 225000, China
2.
State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
3.
Institute of Estuarine and Coastal Research, School of Ocean Engineering and Technology, Sun Yat-sen University, Guangzhou 510275, China

Received Date: 2025-11-11
Rev Recd Date: 2025-12-17

Available Online: 2026-01-06

Publish Date: 2025-12-31

Abstract

Abstract

Based on the measured high-frequency turbulence and salinity profile data from the South Passage of the Changjiang River Estuary in autumn 2020, how water salinity stratification modulates the turbulence viscosity coefficient, drag coefficient, and vertical velocity energy spectrum is quantified, to assess its influence on water-column turbulence. The observation station generally exhibits periodic stratification, with gradual transitions from mixing to stratification during the flood current, and from stratification to mixing during the ebb current. Salinity stratification significantly suppresses the intensity of turbulence in the bottom layer, leading to a decrease in the drag coefficient and viscosity coefficient of the bottom layer. Furthermore, as the height above the bed increases, the reduction in turbulence parameters caused by stratification becomes more pronounced. Spectral analyses of vertical velocity time series at multiple elevations indicate that stratification disproportionately damps low-frequency, large-scale eddies, and that the suppression strengthens away from the bed. Vertically, stratification reshapes the vertical eddy viscosity structure by lowering both the peak and the mean values, shifting the position where the peak occurs downward, and accelerating the decay above the peak, leading to an overall reduction in turbulence. The degree of turbulence suppression is negatively correlated with the height of the stratified region and positively correlated with the intensity of stratification.
- mixing and stratification,
- turbulence,
- eddy viscosity,
- drag coefficient

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References(21)

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